This invention relates to devices for testing and aiding in the hearing of persons having impaired or damaged hearing systems.
Normally, auditory perception or heating is achieved in a human being by having external soundwaves in the air causing corresponding sequential movement of the ear drum membrane, the middle ear stirrup, the inner ear membrane and the fluid in the inner ear, where the movement is detected by the ends of the auditory nerve and transmitted to the brain. Each acts independently of the other and is individually connected to the opposing hemisphere of the brain. Stimuli in the form of nerve impulses perceived by the brain from both auditory nerves is interpreted and correlated as varying noises and tones. However, if the ear drum or other physical components within the normal hearing system are damaged, normal auditory perception is impaired or prevented.
To assist those who have such damaged or impaired hearing, various devices have been proposed and manufactured. One such device provides transmission of audio signals by electrical stimulation of the facial nerve system. This device operates on the principle of transmitting electrically induced audio signals to the facial nerve system which is associated with the inner ear mechanism of the body, such that the signals are transmitted to the hearing centers of the brain. Another device utilizes transmission of sound information to the brain directly through the individual's cranial bone structure, to stimulate the cranial activity to transmit the signals from a source to the brain receptors. Such a device is disclosed and described in U.S. patent application Ser. No. 37,809, filed on May 10, 1979, by the inventors of the device disclosed and described herein.
This device and other prior art devices, while effective, do not provide for intercranial transmission of dual, simultaneous signal sources to test and determine the existence and extent of physical damage to the normal hearing system. Further, none of the prior art systems provides any means to transmit two separate sound signals simultaneously to the brain through the intercranial structure with minimal interference with each other.